Sydney: Babies born to women aged 40 and over from assisted reproduction technologies are likely to have fewer birth defects compared with those from women who conceive naturally at the same age, new research has found.
"There's something quite remarkable occurring with women over the age of 40 who use assisted reproduction," said lead author Michael Davies, Professor at Robinson Research Institute, University of Adelaide in Australia.
"Infertile women aged 40 and over who used assisted reproduction had less than half the rate of birth defects of fertile women of the same age, while younger women appear to be at an elevated risk," Davies noted.
The researchers believe this could point to the presence of more favourable biological conditions in IVF (in vitro fertilization) specific to pregnancies in older women.
Published in the BJOG: An International Journal of Obstetrics & Gynaecology (BJOG), the research is based on data of all live births recorded in South Australia from 1986-2002.
These include more than 301,000 naturally conceived births, as well as 2,200 births from IVF and almost 1,400 from ICSI (intracytoplasmic sperm injection).
The average prevalence of a birth defect was 5.7 per cent among naturally conceived births, 7.1 per cent for the IVF births, and 9.9 per cent for the ICSI births, across all age groups.
In births from assisted reproduction, the prevalence of birth defects was 3.6 per cent for women aged 40 and older using IVF.
For natural conceptions, the corresponding prevalence was 8.2 per cent in women aged 40 plus.
"For women treated with IVF and ICSI combined, the greatest age-related risk of birth defects was among the young women, at or around 29 years of age," Davies said.
"With a prevalence of 9.4 per cent, their risk was more than double the rate of 3.6 per cent observed for the patients aged over 40, and significantly higher than for fertile women of the same age, at 5.6 per cent," Davies noted.